• Advanced Composite Materials
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• v.16 no.4
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• pp.361-376
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• 2007

Disposing of conventional fiber-reinforced polymers (FRPs) poses an environmentally challenging problem. Disposal of FRPs by combustion discharges carbon dioxide in the air because the resin of FRPs is made of fossil fuel. When they are disposed of in the ground, FRPs remain semipermanently without decomposing. In response to these problems, green composites are now being developed and are extensively studied as a material that produces a lower environmental burden. In this paper, green composites using kenaf fiber yarn bundles and PLA (poly(lactic acid)) are fabricated and their tensile properties are evaluated in the experiment. The tensile Young's modulus of all of the laminations is larger than that of PLA alone and the tensile strength of some laminations is larger than that of PLA alone. In particular, the value of UD composite of $0^{\circ$ shows double the tensile strength of PLA alone. Furthermore, the molding conditions for fabricating with a hot press are investigated and the heat resistant tensile properties of green composites are also reported.

• Journal of Mechanical Science and Technology
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• v.17 no.2
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• pp.310-317
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• 2003

The world is faced with a problem of air pollution due to the exhaust emissions from automobile. Recently, lots of researchers have been attracted to develope various alternative fuels and to use renewable fuels as a solution of these problems. There are many alternative fuels studied in place of diesel fuel made from petroleum. Biodiesel fuel (BDF) is a domestically produced. renewable fuel that can be manufactured from vegetable oils, used vegetable oils, or animal fats. In this study, the usability of BDF, one of the oxygenated fuels as an alternative fuel for diesel engines was investigated in an IDI diesel engine. Emissions were characterized with a neat BDF and with a blend of BDF and conventional diesel fuel. Since the BDF includes oxygen of about 11 %, it could influence the combustion process strongly. Therefore, the use of BDF resulted in lower emissions of carbon monoxide and smoke emissions with some increase in emissions of oxides of nitrogen. It is concluded that BDF can be utilized effectively as a renewable fuel for IDI diesel engines.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.1-9
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• 2018

Microalgae is considered as one of environmentally sustainable and potential feedstocks to produce biodiesels. However, recent studies on life cycle assessments (LCA) of microalgal buidiesels have shown that energy requirement is not small to produce biodiesel from microalgae, especially during cultivation stage. The costs for carbon sources, nutrients like nitrogen or phosphorous, and water for cultivation can contribute up to 80% of the total medium costs. In the present article, recent trends on the utilization of several promising nutrient sources such as municipal wastewaters, organic fertilizers, combustion exhaust emissions and organic solid wastes were reviewed, and the potential strategies to be used as substitutes of artificial culture media, especially for the biodiesel production, were discussed.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.49-55
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• 2014

In this study, boiler tube thickness measurement and numerical analysis were conducted for standard 500MW coal-fired power plant in order to research the mechanism of tangential-fired boiler corrosion empirically. The most dominant corrosion mechanism of tangential-fired boiler waterwall was corrosion by sulfur contained in the unburned carbon. And the secondary mechanism was $H_2S$ gas corrosion at localized reducing atmosphere. It is required to decrease the air-stage combustion operation in order to mitigate the waterwall tube corrosion. Also stringent coal pulverization quality control and reinforcing work for corrosion susceptible area such as anti-corrosion coatings is required

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.79-104
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• 2018

A detailed literature review is presented for the applications of the heat pump technologies on the electric vehicles Heating, Ventilation and Air Conditioning (HVAC) system. Due to legal regulations, automotive manufacturers have to produce more efficient and low carbon emission vehicles. Electric vehicles can be provided these requirements but the battery technologies and energy managements systems are still developing considering battery life and vehicle range. On the other hand, energy consumption for HVAC units has an important role on the energy management of these vehicles. Moreover, the energy requirement of HVAC processes for different environmental conditions are significantly affect the total energy consumption of these vehicles. For the heating process, the coolant of internal combustion (IC) engine can be utilized but in electric vehicles, we have not got any adequate waste heat source for this process. The heat pump technology is one of the alternative choices for the industry due to having high coefficient of performance (COP), but these systems have some disadvantages which can be improved with the other technologies. In this study, a literature review is performed considering alternative refrigerants, performance characteristics of different heat pump systems for electric vehicles and thermal management systems of electric vehicles.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.398-405
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• 2003

A fast response analyzer for measuring carbon dioxide concentration has been developed for transient characteristic and researches tested on internal combustion engine. The analyzer uses the well known NDIR(Non-Dispersive Infrared) method with miniaturized detection system, giving a time constant of approximately 30 microsecond, and sampling module consists of capillary tube. Since the transit time and the time constant of the sampling system depend on the sampling conditions, it is necessary to investigate the characteristics of sampling system before applied to exhaust gas measurement in engine. A unique method was designed to study the influence of the diameter of transfer sample line and operating conditions of the FRNDIR on transit time and time constant. A database of transit time and time constant was built up for different measured and simulated pressure conditions. The database can be used for correcting eventual $CO_2$ concentration measurement.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.407-410
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• 2002

Hydrogen is considered to be a clean energy because it doesn't generate the global warming gas such as $CO_2$, SOx and NOx, after its combustion. In this study, strain YJ isolated from shore system was used to produce efficiently hydrogen using the various carbon sources such as glucose, sucrose and fructose and its characteristics were investigated in batch cultivation. The maximum hydrogen production shown that glucose, sucrose and fructose were highest obtained at 2, 4 and 5 % concentration, respectively. In addition, we investigated the effect of pH under various conditions as range of initial pH 5.5 to 8.0 pH because growth of strain YJ declined due to produced organic acids. The results showed that the highest production rate of hydrogen was obtained at pH 7.5.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.3
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• pp.281-290
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• 2004

The main purpose of this study was to characterize the air pollutants emission factors in electric power plant (EPP) using fossil fuels. The electric power plant is a major air pollution source, thus knowing the emission characteristics of electric power plant is very important to develop a control strategy. The major air pollutants of concern from EPP slacks are particulate matter (PM), sulfur oxides (SOx), nitrogen oxides (NOx), carbon monoxide (CO) and heavy metals. Throughout the study, the following results are estimated - PM : 8.671E-05 ∼ 8.724E+01 PM emission (kg) per fuel burned (ton) - SOx : 4.149E-04∼7.877E+01 SOx emission (kg) per fuel burned (ton) - NOx 1.578E-02∼9.857E+00 NOx emission (kg) per fuel burned (ton) - CO : 3.800E-04∼1.291E+00 CO emission (kg) per fuel burned (ton) - Hg : 1.220E+01∼3.108E+02 Hg emission (mg) per fuel burned(ton) From the statistical analysis by Wilcoxon signed ranks test between the emission factors of ours and U.S. EPA's, we can yielded that : p 〉0.05.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.129-139
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• 2002

From the view of the environmental protection against the use of fossil fuels, a great of efforts have been exerted to find an alternative energy source. Hydrogen may become an alternative. However the product species of the hydrogen flame is only $H_2O$, which emits only non-luminous radiation so the radiation from it is much smaller than that for a hydrocarbon flame. In this study, the authors designed and fabricated a laboratory scale test furnace to study thermal characteristics of hydrogen-air diffusion flame. In addition, the effects of addition of reacting as well as non-reacting solid particles were experimentally investigated. Among the total heat flux to the wall, about 75% was occupied by radiation while 25 % by convection. When the aluminum oxide ($Al_2O_3$) particles were added, the radiative heat flux was reduced due to heat blockage effects. On the other hand, the total as well as the radiative heat flux was increased when the carbon particles were seeded, since the overall temperature increased. The effects of swirl and excess air ratio were also examined.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.413-417
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• 2003

The last few decades have seen drastic growth in the use of brominated flame retardants(BFRs). There is the problems of polybrominated dibenzo-p-dioxins(PBDDS) and polybrominated dibenzofurans(PBDFs) generation as by-products in combustion process of BFRs. PBDDs/PBDFs are highlighted the new pollutants of environmental contamination, recently. In this study, the 10 kinds of PBDDs/PBDFs standards were used to perform the experiments of recoveries. The analysis of PBDDs/PBDFs in soil environmental samples. was carried out. In silica gel column cleanup, PBDDs/PBDFs eluted until 80mL of n-hexane, and the recovery was obtained 73∼105%. In multi-layer silica gel column cleanup, the recovery was obtained 56∼125% with various elution solvents. In alumina clean process, the standard mixture(PBDES, PBDDs/PBDFs) eluted the first fraction of 2% dichloromethane with n-hexane in the range of 0∼100mL, PBDEs compounds eluted in the second fraction of 50% dichloromethane with n-hexane. In activated carbon column cleanup, the PBBEs eluted to the first fraction(n-hexane) and second fraction(toluene), but PBDDs/PBDFs only eluted to the second fraction. The analytical methods of PBDDs/PBDFs for soil was established based on the experimental results of the environmental samples.